Law works best when it reflects shared intuitions and morals. Otherwise, many would find ways and reasons to bend or break it. This is partly why legal systems across continents and centuries have strikingly similar rules and principles. People follow them because they channel natural tendencies in ways that benefit their communities. Law structures life, and so life follows law.

What some lawyers don’t get about President Duterte is that he represents a legal principle that springs from a widely shared intuition. It is a principle as ancient as Rome and as present as the US war on terror. Necessitas legem non habet—Latin for “necessity has no law”—means some fundamental laws may be suspended if necessary to defend the motherland. A few of history’s greatest statesmen have endorsed it. Abraham Lincoln, for example, acted as an absolute dictator for 10 weeks after the American civil war began. He ruled by decree, suspended the privilege of the writ of habeas corpus, censored the mail, and had the military arrest and detain suspects. “Whether strictly legal or not,” he explained to Congress, his actions were justified by “what appeared to be a popular demand and a public necessity.”

Our Constitution recognizes the necessitas principle. It says that “whenever it becomes necessary,” a president may call out the army, suspend the privilege of the writ of habeas corpus, or declare martial law. It also allows the temporary takeover of critical businesses during “times of national emergency.” Mr. Duterte started invoking the principle during his election campaign. The people hear him because it reflects their intuitions. Unlike most lawyers, they don’t need the formalities of, say, an official martial law proclamation to see what is going on.

“We are already in stage 2” of a social cancer, Mr. Duterte has said about the drug problem. His chemotherapy: “If you destroy my country, I will kill you.” This tough talk is not mere bluster. The police and vigilantes have killed at least 6,000 suspects in his first six months in office. According to a recent SWS survey, nearly 8 of 10 Filipinos are scared for their lives. The same survey shows that despite their fears, above 8 of 10 Filipinos still support the President.

Extrajudicial killing is a crime. Mr. Duterte knows it. His supporters know it. No one honestly believes that the standard police excuse, resisting arrest, is true in most cases. Even Mr. Duterte was apologetic when he explained away as “collateral damage” the innocents killed in his war on drugs. The 8 of 10 Filipinos who put their trust in his bloodstained hands do not do so because they think the killings are legal. They back him because they believe his claim that the killings are needed to prevent drug lords and addicts from destroying the country. Necessitas legem non habet.

EJK is thus an issue, not of legality, but of legitimacy. It will continue as long as enough people believe it is needed to defend the country. No amount of legal reasoning can change that.

What the law can do is change the stakes. Necessity has no law for what happens after a crisis to those who invoke it. Cicero and Napoleon were exiled. Robespierre and Eichmann were executed. Lincoln and Roosevelt were prudent to invoke necessitas before the US Congress to obtain its support. Getting Congress or the Supreme Court on your side during a crisis lowers the stakes for illegal acts.

Because they have the means to act first, executives enjoy wide discretion to deal with a crisis at the outset. But as soon as it is able, Congress is duty-bound to declare if there really is a crisis and what measures are necessary to meet it. Courts can also determine if either the president or Congress acted too brutally during a crisis. Law in this way resolves an issue of legitimacy by requiring emergency presidential power to seek congressional and judicial authority.

Given its duty, Congress cannot continue to fiddle while the country burns. Its inquiries must lead not only to new laws but also to a declaration of its position on the President’s emergency measures.

Bryan Dennis Gabito Tiojanco is a doctoral student at Yale Law School and a Yale Fox International Fellow at the National University of Singapore. He graduated cum laude from the University of the Philippines College of Law.